Before you go into perspective or loose drawings make sure that you can visualize your pictures. If possible fix your problems in your thumbnails, because that’s when it’s easiest to make changes. Here are a couple of links for some great design principals.
Perspective is one of the necessary evils of drawing, but it’s not too hard to learn. The most important ones to learn is 1 and 2 point perspective. 3 point perspective is also fun, but most useful if you are drawing the tops of buildings/from an overhead perspective. Three point perspective can also be used to draw an object floating/above the ground.
I learned perspective in high school. We may have gone over it briefly in university, but being out of practice for so long makes remembering the finder details difficult. I’ve recently had to do a refresher myself to reacquaint myself with perspective. Instead of explaining it myself I’m going to give you links for 3 great videos and some extra explanation for one point perspective!
One Point Perspective: https://www.studentartguide.com/articles/one-point-perspective-drawing
https://thevirtualinstructor.com/onepointperspective.html (video and reading/pictures of what’s in the video)
Two Point Perspective: https://thevirtualinstructor.com/twopointperspective.html (video and reading/pictures of what’s in the video)
Three Point Perspective: https://thevirtualinstructor.com/threepointperspective.html (video and reading/pictures of what’s in the video)
It helps me to work on a full-sized loose version of all my drawings before I start on my finals. Some people find it helpful to use a copier or their computer to increase the size of their thumbnails and draw on top of that.
Some people work best going straight into their full sized work after they finish their thumbnails. How you want to proceed is up to you. If you aren’t sure at all how to proceed, please ask!
The finals can be somewhat sketchy. There will be some final images to include with your dummy so an editor/agent/art director can better envision the final book.